Population thinking
Barrett’s philosophical engine, imported in Barrett (2017) from Mayr’s reading of Darwin.
The move
Before On the Origin of Species, a species was a type: a set of unchanging physical characteristics passed down the generations. Darwin’s innovation was to replace the type with a population of physically unique individuals whose similarities are defined functionally, not physically. A species is a reproductive community — grouped by what its members do, not by a shared feature set or even a shared gene pool.
Typological thinking has a characteristic failure mode, and Barrett spells it out in a footnote: it “fundamentally underestimates within-category variation… and over-estimates between category variation,” and borderline cases keep showing up. Anyone who has read the autonomic-specificity-of-emotion literature will recognize the symptom.
Applied to emotion:
My hypothesis, following Darwin’s insight, is that fear (or any other emotion) is a ‘category’ that is populated with highly variable instances. The summary representation of any emotion category is an abstraction that need not exist in nature.
Biological categories are conceptual categories. So are emotion categories — and so, Barrett adds, are the categories of social reality: flowers and weeds, money, currency. “Functions are imposed on physically disparate instances by virtue of collective agreement.”
The diagnosis this licenses
Population thinking is what lets Barrett explain not just why the classical view is wrong but why intelligent people keep believing it:
The fact that human brains effortlessly and automatically construct such representations helps to explain why scientists continue to believe in the classical view and even propose it as an innovation, even as evidence continues to call it into doubt.
The summary representation feels like the thing itself. That is what a concept is for — and it is also, on this account, why a century of researchers have looked at averaged data and seen an essence. The theory explains its own opposition as an instance of the mechanism it describes. Elegant, and not entirely fair: an argument that accounts for your opponents’ persistence by their cognitive architecture is one that cannot lose.
The Darwin irony
Barrett makes a point she plainly enjoys: the theory of constructed emotion is consistent with On the Origin of Species (1859) and inconsistent with The Expression of the Emotions in Man and Animals (1872). The basic-emotions tradition claims descent from Darwin — but from the wrong book, and from the one that abandoned his own central innovation. In the Expression, emotions are types with fingerprints; in the Origin, categories are populations. She notes elsewhere the field has built on “a very selective reading of Darwin.”
The convergence nobody in the sources notices
This is the finding the wiki should record loudest, because it is invisible from inside either source.
Scarantino (2018) — Barrett’s opponent, defending basic emotion theory — makes structurally the same move against essentialism, and gets the opposite conclusion:
| anti-essentialist device | philosopher | paradigm case | conclusion | |
|---|---|---|---|---|
| Barrett | population thinking | Mayr (via Darwin) | species | categories are conceptual → emotions are constructed |
| Scarantino | HPC kinds | Boyd | species | kinds need no essences → basic emotions survive the variability |
Both say: essentialism is the error, biological species are the model, within-category variability is expected rather than damning. Both cite species as the paradigm case. And then one concludes emotions are constructed and the other concludes basic emotion theory was never threatened.
That tells you where the real disagreement is, and it is not about essentialism — both have abandoned it. It is about whether a variable, functionally-grouped category can still be causally potent: Scarantino keeps the probabilistic latent variable (emotions cause expressions and autonomic changes), Barrett does not (categorizations are the events, and nothing underlying them causes them). See basic-emotions for the four-way comparison and locationist-vs-constructionist-brain-emotion for what the imaging data can and cannot say about it.
The statistical corollary
The most quotable thing in the source, and the one with practical consequences for reading this wiki’s empirical pages:
A pattern that diagnoses sadness is not the brain state for sadness but merely a statistical summary of a highly variable set of instances. To assume otherwise is an essentialist error that mistakes a statistical summary for the norm.
With the footnote: “The average size of a US family in 2015 was 3.14 persons, but that does not mean that every family (or even any family) contained 3.14 people.”
Barrett notes the voxels making up a category pattern “need not [be] observed in every (or even any) single instance of that category” — confirmed, she says, by mathematical simulation (Clark-Polner, Johnson & Barrett, 2016) and prefigured by Posner & Keele (1968) half a century earlier.
Worth applying to the wiki’s own material, including the material that appears to favour her opponents: the group-averaged bodily sensation maps of Nummenmaa and Volynets are statistical summaries over thousands of subjects. Whether any individual feels anger the way the averaged anger map depicts is a question those papers do not ask and their design cannot answer.